/Engine/Source/Runtime/Slate/Public/Framework/Application/SlateApplication.h
Takes a screenshot of the widget writing the results into the color buffer provided. Note that the format is BGRA. the size of the resulting image is also output.
true if taking the screenshot was successful.
bool TakeScreenshot ( const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > & Widget, [TArray](API\Runtime\Core\Containers\TArray)< [FColor](API\Runtime\Core\Math\FColor) > & OutColorData, FIntVector & OutSize )